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FLUENT V6 - how to workaround the "invalid window id" error when you have 20 or more monitors defined with your run

If you define 20 or more monitors in your FLUENT run, you may see a "Invalid Window ID" error when you begin the calculation.
The problem lies in a limit of 20 windows that can be opened from within FLUENT (numbered 0-19). However, this error occurs even if you are only using the 'print' and/or 'write' options (not plot). This is because FLUENT still checks the window index set in the monitor panel, even if you are not using the plot option. By default, the window index is equal to the monitor number. Hence, for monitors 20 and greater, the window index is greater than the maximum allowed (19).

The workaround is to simply set the plot window # to 19 or lower. This will allow the definition of 20 or more monitors. Note that you will not be able to plot to more than 20 windows.